Ion exchanger from chemically modified banana leaves

•Banana leaves were treated with different molarities of KMnO4.•Phosphorylation of banana leaves increased its efficiency toward ion uptake.•Thermal stability of the carboxylated and phosphorylated banana leaves at high temperature gave best results. Cation exchangers from chemically modified banana leaves have been prepared. Banana leaves were treated with different molarities of KMnO4 and cross linked with epichlorohydrin and their effect on metal ion adsorption was investigated. Phosphorylation of chemically modified banana leaves was also studied. The metal ion uptake by these modified banana leaves was clarified. Effect of different varieties, e.g. activation of produced cation exchanger, concentration of metal ions was also investigated. Characterization of the prepared ion exchangers by using infrared and thermal analysis was also taken in consideration.